The taking of radiographic images of an object of study, whether a patient or an object, from different angles, positions and/or distances (“poses”, a term that is widely used within this technological field), has acquired special relevance in fields such as medicine, surveillance and industrial production. In particular, it is very useful identifying, in a radiographic image, information corresponding to the location of points of interest which are present in other radiological image of the same object of study, which has been generated from a different location and/or orientation (pose).
This objective of obtaining several radiographic images of the object of study at different positions in order to obtain expanded information is typically performed using computed tomography (CT). However, in the case of industrial or medical applications, in which this technique is primarily used, such as for the preliminary analysis of the object of study, where efficient operation requires equipment that is modest and, at the same time, relatively fast, CT technology is particularly expensive and complex. Moreover, the use of CT instruments requires adopting a number of international principles related to safety and the ALARA radiological protection criteria.
There is an alternative, using only radiography systems, which has a lower cost and greater availability, but nonetheless is not exempt from the initial difficulty arising from the fact that the image produced is two-dimensional and, in order to perform a three-dimensional reconstruction, the relative locations of the source of X-rays with respect to the plate that acts as the X-ray sensor or the object of study are not known with sufficient precision. In other words, the pose of the system is not known. Moreover, it is complicated to obtain, from the record of several radiographic images, three-dimensional information about areas of interest that are simultaneously present in different shots from different distances and orientations. In particular, when the object of study is a patient, there are more strict requirements due to the underlying clinical interest.